1. Field of the Invention
The field of art to which this invention pertains is the separation of unsaponifiables from fatty and rosin acids by a process employing liquids to effect the removal of the unsaponifiables.
2. Background Information
There is a wealth of patent art teaching the separation of unsaponifiables from tall oil soap using liquid-liquid extraction schemes. Examples of such schemes are as disclosed in U.S. Pat. Nos. 3,965,085 to Holmborn et al., 3,803,114 to Mitchell et al. and 2,530,809 to Christenson et al. In these schemes unsaponifiables are extracted from aqueous solution with salts of fatty and rosin acids by contacting the solutions with a solvent, such as a hydrocarbon, in which the unsaponifiables are soluble and thereby removing the unsaponifiables from the salts. The fatty and rosin acid salts, according to these references, may then be converted to the acid forms to obtain tall oil.
With further regard to the above mentioned Mitchell et al. patent, it is taught (column 4) that emulsions formed when the attempt is made to extract unsaponifiables from aqueous solutions with a hydrocarbon solvent cause a serious problem which prevents successful completion of the extraction. This "problem" was solved by the use of certain alcohols which acted as de-emulsifiers. The teaching goes on to state that if water, soap skimmings, alcohol and hydrocarbon were shaken up together, the unsaponifiables would be extracted by the hydrocarbon and, when the mixture was allowed to stand, the components would quickly separate into a lower phase, consisting mainly of soap-water-alcohol, and an upper phase consisting mainly of hydrocarbon and unsaponifiables.
The present invention, in marked contradistinction to the known processes, effects the separation of unsaponifiables from fatty and rosin acids (not salts) and requires, as an essential step of the process, the formation of an emulsion.